msm: kgsl: Enable GMU power counters if accessible

GMU power counters needs to be initialized to get the
proper busy cycles. If GMU is not enabled, the 
perfcounters are still accessible. Allow GMU power
counter initialization even if the GMU is disabled
to get the GPU busy cycles data.


Change-Id: I28cf83be45c32b1b24891b3a7d321834d157e092
Signed-off-by: Hareesh Gundu <hareeshg@codeaurora.org>